The recent growth of the Internet has increased the demand for bandwidth. Digital subscriber line (DSL) technology meets this demand by providing higher bandwidth data service over existing twisted pair telephone lines. DSL technology achieves the higher data transmission rates by taking advantage of unused frequencies, which are significantly higher than voice band frequencies, on the existing twisted pair lines.
DSL systems typically include multiple bundles of twisted pair wires that may be located within close proximity of each other. Communication occurring on one wire may degrade or substantially interrupt communication on an adjacent wire by causing crosstalk on the adjacent wire. DSL systems typically can suffer from two different types of crosstalk. Far end crosstalk generally occurs between signals being transmitted at the same time and in the same direction on two adjacent wires. Far end crosstalk typically may not be avoided and may only limit the speed of communication in the system. In contrast, near end crosstalk generally occurs between signals on adjacent lines being transmitted at the same time but in opposite directions. Near end crosstalk, however, has a more detrimental effect on communication in the system and may even destroy weak line communication if it is not eliminated.